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<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
</head>
<body>
    <script>
    // 1.类的继承
    // class Father {
    //     constructor () {

    //     }
    //     money() {
    //         console.log(100);
    //     }
    // }
    // class Son extends Father {

    // }
    // var son = new Son();
    // son.money();

    class Father {
        constructor(x, y) {
            this.x = x;
            this.y = y;
        }
        sum(){
            console.log(this.x + this.y);
        }
    }
    class Son extends Father {
        constructor(x, y) {
            super(x, y);  // 调用了父类中的构造函数
        }
    }
    var son = new Son(1, 2);
    son.sum();
    </script>
</body>
</html>